1. Field of the Invention
This invention relates generally to a system and method for adjusting the brightness of an image to be photographically reproduced and, more particularly, to a system and method for adjusting the image brightness in a system in which the images are displayed for photographic reproduction.
2. Description of the Prior Art
Electronic image copiers which utilize a cathode ray tube to display an image to be photographically reproduced by exposing a photosensitive material to the display screen of the cathode ray tube are well known in the art. Such images to be photographically reproduced may be displayed on the cathode ray tube at conventional video frame rates. Full color reproductions may be made by using a monochromatic cathode ray tube to sequentially display the red, green and blue color separation video signals through filters in a way that synchronizes the color of the filter to the color of the video signal being displayed on the screen. Alternatively, a color cathode ray tube could be used to display the full color image for photographic reproduction. Regardless of the aforementioned technique utilized, the brightness of the cathode ray tube must be adjusted before each exposure to assure its correlation to the photosensitive characteristics of the film to be exposed. The brightness of a cathode ray tube for a given input voltage may vary considerably with time particularly during the warm-up period for the cathode ray tube which may extend for several minutes. Thus, it is necessary that the cathode ray tube be adjusted before each exposure so that for a given input voltage there is provided a select brightness on the display screen of the cathode ray tube which correlates to the light sensitivity characteristics of the photoresponsive material to be exposed. The adjustment of the cathode ray tube brightness to a select reference level, however, may not be sufficient to accommodate for the variation in brightness levels of the different images that may be displayed for photographic reproduction. Thus, depending upon the image scene brightness characteristics a satisfactory exposure still may not be provided despite the aforementioned brightness adjustment since there may still be an insufficient correlation between the scene brightness characteristics and the light sensitivity characteristics of the film to achieve a satisfactory photographic reproduction.
Therefore, it is a primary object of this invention to provide a system and method for adjusting the image brightness in a display from which a photographic reproduction is exposed which accounts for the variation in the brightness characteristics of different images.
Other objects of the invention will be in part obvious and will in part appear hereinafter. The invention accordingly comprises a mechanism and system possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.